Please enable JavaScript.

Coggle requires JavaScript to display documents.

Research Paper, Maybe the details of manufacturing process (eg advantage)…

- - - - 3D printing
        
        part
        
        rotor blade
        
        flap support
        
        to contain the shape of the paper
        
        advantage
        
        light
        
        low cost
        
        great quality
        
        easy to operate
      - CNC machining
        
        part
        
        end plate (acrylic)
        
        advantage
        
        precise cutting
        
        enable good fitting during assembly
    - - height
        
        150mm
        
        fit into test section
      - blade thickness
        
        3 mm
        
        reduce contact area
        
        reduce negative torque
      - end plate ratio
        
        1.1
        
        optimal ratio
      - aspect ratio
        
        AR = 0.7
        
        higher static torque coefficient
      - blade profile
        
        elliptical
        
        47.5 deg
        
        better performance (23.6%)
      - blade number
        
        2 blades
        
        better performance
    - - attached flap
      - paper - light material
      - working principle
        
        flap - one-way valve
        
        open at advancing blade
        
        closes at returning blade
        
        reduce negative torque
        
        preserve positive torque
  - - - full flap
      - half flap
    - - 20% flap
      - 30% flap
      - based on pressure contour (Alom)
    - - unflapped
      - 20% full-flap
      - 30% full-flap
      - 20% half-flap
      - 30% half-flap
  - - - pulley
      - load cells
        
        measure braking load
      - braking belt
      - Hall effect sensor
        
        tachometer
        
        measure RPM
      - digital display
  - - - ratio of Pout to Pin
    - - ratio of generated torque to available torque
    - - ratio of tip speed to flow speed
- - - - Broad
        statement
        
        Overview
        
        Non-renewable energy
        
        Primary energy source
        
        Types
        
        Oil
        
        Gas
        
        Coal
        
        Nuclear
        
        Negative effect/ Drawback
        
        Greenhouse gases/ global warming
        
        depletion of source
        
        carbon emission
        
        Renewable energy
        
        Types
        
        Solar
        
        Geothermal
        
        Hydropower
        
        Advantages
        
        5 more items...
        
        wind
        
        Advantages
        
        clean energy
        
        less carbon emission
      - Renewable energy in Malaysia
        
        Problems
        
        Low electrification rate
        
        remote area
        
        non-economic
        
        Electricity demand increases
        
        Why not other techniques?
        
        solar
        
        high solar radiation
        
        high cost
        
        wind
        
        poor wind resource
        
        why hydropower?
        
        close to river
        
        low cost
  - - - HKT
        
        Primary modes of HKT
        
        Horizontal axis rotor
        
        Optimal for high water velocity
        
        High efficiency
        
        ocean current application
        
        Vertical axis rotor
        
        Low noise
        
        river current application
        
        Simpler design
        
        Lower water flow rate
        
        Specific focus
        
        Major types
        
        Savonius
        
        drag-based
        
        advantages
        
        good self-starting performance
        
        operates under much lower flow rates
        
        simple design
        
        low noise
        
        high static torque
        
        disadvantages
        
        relatively low efficiency
        
        3 more items...
        
        working principal
        
        drag difference
        
        configuration
        
        advancing blade
        
        returning blade
        
        Darrieus
        
        advantage
        
        relatively high efficiency
        
        disadvantage
        
        poor self-start ability
        
        more demanding design
        
        lift based
      - Types of hydropower
        
        Conventional
        
        Working principle
        
        Gravitational potential energy
        
        water reservoir, dam
        
        Disadvantages
        
        destructive to ecosystem
        
        manufacturing of concrete produce pollutions
        
        greenhouse gaseous (decomposition of biomass)
        
        Non-conventional (HKT)
        
        working principle
        
        kinetic energy of free flowing water
        
        do not require large water storage
        
        advantages
        
        more potential sites available
        
        do not interfere with natural ecology
- - - - General problem(s)
        to investigate
        
        negative torque
        
        low efficiency
      - Specific problem(s)
        to investigate
        
        Poor flap design
        
        Lack of experimental research on dynamic venting
    - - Specific aim(s)
        to achieve
        
        Conduct experimental evaluation
        
        Design new flap - lighter
        
        Optimize flap configuration
- - - - External Modification
        
        Salleh, ECM 2020
        
        Key experiment Set-up
        
        Advancing blade longitudinal position
        
        X_A/R = 0.000
        
        X_A/R = -0.250
        
        X_A/R = -0.500
        
        Returning blade longitudinal position
        
        X_R/R = -1.204
        
        X_R/R = -1.454
        
        X_R/R = -1.704
        
        Deflector height
        
        0.5H
        
        1.0H
        
        1.5H
        
        Without deflector
        
        Result
        
        Experiment
        
        Advancing blade longitudinal position
        
        Highest Cpmax increment at X_A/R = -0.500
        
        Deflector acted like contracting nozzle
        
        Accelerated flow towards adv. blade
        
        Returning blade longitudinal position
        
        Highest Cpmax increment at X_R/R = -1.204
        
        Inhibited incoming flow hitting on returning blade
        
        X_R/R influence performance more than X_A/R
        
        Deflector height
        
        1H shows best performance
        
        effectively block the flow towards returning blade
        
        Parameters at highest performance
        
        Cpmax = 0.26
        
        CT at Cpmax = 0.28
        
        TSR = 0.92
        
        Improvement = 100%
        
        Objective
        
        Effect of blade deflector longitudinal position ratios and deflector's height on power performance of Savonius turbine
        
        Figure
        
        Key info of this paper
        
        reducing negative torque increases performance
      - Internal Modification
        
        Static Venting
        
        Rathod, 2019
        
        Objective
        
        Effect of capped vents (CVs) on torque distribution of Savonius turbine
        
        Key experiment Set-up
        
        CV
        
        Conventional blade
        
        7% CV blade
        
        21% CV blade
        
        14% CV blade
        
        Result
        
        Experimental
        
        CV blades shows poor performance
        
        Higher CV ratio, lower Cp and CT
        
        CV blades has smaller working tip-speed ratio range
        
        20-35% performance decrement for 21% CV blade
        
        Numerical
        
        agrees with experimental result
        
        leakage of high energy fluid through CV
        
        formation of vortices
        
        local torque coefficient (C_LT)
        
        2 more items...
        
        Key info for this paper
        
        venting location at center of rotor is not preferable
        
        Alom, Energy 2018
        
        Key experiment Set-up
        
        Profile
        
        Elliptical
        
        1 more item...
        
        Semicircular
        
        venting
        
        vent-augmented
        
        non-vented
        
        result
        
        experimental
        
        agrees with numerical result
        
        vented elliptical shows best result
        
        CPmax = 0.146 at 0.49 TSR
        
        23.06% improvement compared to conventional semicircular
        
        8.08% improvement compared to unvented elliptical
        
        numerical
        
        47.5 deg cut angle is best
        
        3 more items...
        
        Venting improves performance
        
        3 more items...
        
        figure of pressure contour
        
        2 more items...
        
        Objective
        
        Performance evaluation of vent-augmented elliptical-bladed Savonius rotor
        
        Key info of this paper
        
        rotor configuration (elliptical)
        
        pressure distribution --> suitable vent location
        
        venting works
        
        Dynamic Venting
        
        Reupke, AE 1991
        
        result
        
        experimental
        
        Flaps locked due to centrifugal force
        
        Noisy during operation
        
        Lower performance than unmodified rotor
        
        lighter flaps has better dynamic performance
        
        1 more item...
        
        modified rotor selfstart >4m/s
        
        Objective
        
        Performance evaluation of slatted-blade Savonius wind rotor
        
        Key experiment Set-up
        
        modified rotor
        
        8 hinged flaps
        
        16 hinged flaps
        
        unmodified S-rotor
        
        figure
        
        Key info of this paper
        
        heavy flap is not preferrable
        
        Borzuei, 2021
        
        Objective
        
        Performance evaluation of one-way opening valve on the three blade Savonius wind turbine
        
        Key experiment Set-up
        
        Valve size
        
        small
        
        1 more item...
        
        large
        
        1 more item...
        
        Valve opening direction
        
        Clockwise (CW)
        
        Counter-clockwise (CW)
        
        Valve opening limit
        
        limited (45 deg)
        
        unlimited
        
        Result
        
        Numerical
        
        Improved performance
        
        2 more items...
        
        Poor performace
        
        1 more item...
        
        Key info of this paper
        
        rotor configuration & flap location etc is important
- - - - CP graph
        
        TSR 0.66 ~ 0.78 = CPmax
        
        Cp of flapped rotor > unflapped
        
        graph trend
        
        TSR decrease, Cp increase
        
        after Cp max, decrease in TSR causes Cp to drop
        
        A Cp max is reached
      - Cp improvement graph
        
        30 Half > 30 Full > 20 Full > 20 Half
        
        based on difference to the Cpmax of unflapped
        
        Table summarizes all important data
      - CT graph
        
        flapped > unflapped
      - all self start
    - - higher CP
        
        reduce negative pressure - venting
        
        conserve positive pressure
        
        flap opens at returning
        
        flap closes at advancing
        
        overall higher net positive torque
        
        reter to CT graph
  - - - CP graph
        
        sudden drop at 0.7 ~ 0.8 TSR.
        
        Cp of flapped rotor > unflapped
        
        TSR 0.68 ~ 0.81 = CPmax
        
        graph trend
        
        TSR decrease, Cp increase
        
        after Cp max, decrease in lambda causes Cp to drop
        
        A Cp max is reached
        
        similar to 5m/s
      - Cp improvement graph
        
        20 Half > 30 Full > 20 Full > 30 Half
        
        based on difference to the Cpmax of unflapped
        
        Table summarizes all important data
      - all self start
      - CT graph
        
        flapped > unflapped
    - - higher CP
        
        vent out undesired pressure
        
        dynamic venting mechanism
        
        increase net positive torque
      - sudden drop in Cp
        
        Sommerfeld effect
        
        vibration/ resonance phenomenon
        
        factors
        
        setup error
        
        misalignment of turbine
        
        unbalanced load
        
        matches natural frequency
        
        CT decreases sharply
        
        energy not resulted in higher RPM
        
        but in higher vibration
  - - - 5 m/s
      - speed < 5 m/s --> low performance
    - - 7m/s
      - speed > 7m/s --> strong vibration
    - - Re
      - atmospheric condition
        
        temperature
        
        density
        
        dynamic viscosity
    - - typical river speed: 0.2 ~ 0.6 m/s
      - equivalent wind speed: 3.8 ~ 11.4 m/s
  - - - 30% full-flap > 20% full-flap (5 & 7 m/s)
        
        more effective in venting
        
        higher net positive torque
        
        larger vent size
      - After a particular TSR, full flap performance < unflapped
        
        flap locks
        
        centrifugal force
        
        unknown of why the performance is lower than benchmark
        
        refer to Reupke's paper
        
        maybe due to surface unevenness?
      - After a particular TSR, 30% full flap < 20% full flap
        
        flap locks
        
        centrifugal force
        
        larger flap = heavier
    - - 30% half-flap < 20% half-flap (7m/s)
        
        larger flap = heavier
        
        poor dynamic performance
        
        flap locks
        
        high centrifugal force
        
        formula of centrifugal force, Fr
        
        m increase, Fr increase
        
        TSR increase, Fr increase
        
        U increase, Fr increase
        
        dynamic venting is suitable at low speed
        
        inhibits venting
      - 30% half-flap > 20% half-flap (5m/s)
        
        vents more
        
        larger vent size
  - - - flap location
        
        flap designed at high pressure region
        
        effectively vents out negative pressure
      - light flap
        
        good dynamic performance
- - - - reduce negative torque
      - preserve positive torque
    - - but heavier
      - larger centrifugal force
      - locks at high speed
    - - lower centrifugal force
      - better dynamic performance
  - - - this project is for hydro application
      - lower flow speed, lower centrifugal force
      - dynamic venting will work better
    - - capture the motion and condition of flap
      - flow visualization technique
        
        able to explain physics
        
        aerodynamic surrounding the flap